https://file.aiquickdraw.com/mathbot/file/1730158553478qkkub697.jpg

The problem in the screenshot involves ranking different solutions by their pH levels, using information about weak acids and weak bases. Let’s break down the task.

### Overview:
You are asked to rank four different solutions according to their pH in **increasing order** (lowest pH to highest pH). These are the given solutions:
1. **0.1 M KNO₂**
2. **0.1 M NaCH₃CO₂**
3. **0.1 M CH₃NH₃Cl**
4. **0.1 M KBr**

We are given **Ka** values for acids and **Kb** values for bases:
- **Acids:**
  - Acetic acid (CH₃COOH): Ka = 1.8 × 10⁻⁵
  - Nitrous acid (HNO₂): Ka = 4.5 × 10⁻⁴
- **Bases:**
  - Methylamine (CH₃NH₂): Kb = 4.4 × 10⁻⁴
  - Ethylamine (C₂H₅NH₂): Kb = 6.4 × 10⁻⁴

Now let's analyze each solution.

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### Step-by-Step Solution:

1. **0.1 M KNO₂**  
   - **KNO₂** is the salt of a weak acid (HNO₂) and a strong base (KOH).  
   - Since NO₂⁻ comes from a weak acid (HNO₂) with Ka = 4.5 × 10⁻⁴, NO₂⁻ will act as a **weak base** and slightly increase the pH.  
   - This solution will be **slightly basic**.

2. **0.1 M NaCH₃CO₂**  
   - **NaCH₃CO₂** is the salt of acetic acid (CH₃COOH) and a strong base (NaOH).  
   - CH₃CO₂⁻ comes from a weak acid (Ka = 1.8 × 10⁻⁵) and will act as a **weak base**, increasing the pH slightly.  
   - This solution will also be **slightly basic** but with a lower pH compared to KNO₂ because acetic acid is weaker than nitrous acid.

3. **0.1 M CH₃NH₃Cl**  
   - **CH₃NH₃Cl** is a salt formed from methylamine (a weak base, Kb = 4.4 × 10⁻⁴) and a strong acid (HCl).  
   - The CH₃NH₃⁺ ion is a **weak acid** and will lower the pH.  
   - This solution will be **acidic**.

4. **0.1 M KBr**  
   - **KBr** is a salt formed from a strong acid (HBr) and a strong base (KOH).  
   - Neither ion will hydrolyze, so the solution will be **neutral** with a pH of 7.

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### Ranking the Solutions by pH (Increasing Order):
1. **0.1 M CH₃NH₃Cl** – Most acidic (lowest pH)  
2. **0.1 M KBr** – Neutral (pH ≈ 7)  
3. **0.1 M NaCH₃CO₂** – Slightly basic (pH > 7)  
4. **0.1 M KNO₂** – More basic (higher pH than NaCH₃CO₂)

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Would you like further details or clarifications?  
Here are 5 related questions to expand your understanding:

1. How can the pH of a salt solution be calculated explicitly?
2. What determines whether a salt acts as an acid or base in solution?
3. Why does KBr result in a neutral solution?
4. How do the Ka and Kb values influence the relative pH of solutions?
5. What happens to the pH if the concentration of each solution were doubled?

**Tip:** For salts derived from weak acids or weak bases, always look at the conjugate ion's ability to hydrolyze and affect pH.

Consider the following data on some weak acids and weak bases, and rank the following solutions in order of increasing pH:

1. 0.1 M KNO₂
2. 0.1 M NaCH₃CO₂
3. 0.1 M CH₃NH₃Cl
4. 0.1 M KBr

Using Ka and Kb values provided for acetic acid, nitrous acid, methylamine, and ethylamine.

Learn how to rank the pH levels of various salt solutions, including 0.1 M KNO₂, NaCH₃CO₂, CH₃NH₃Cl, and KBr, using given Ka and Kb values for acetic acid, nitrous acid, methylamine, and ethylamine. Understand the acid-base properties of salts and how to determine the pH behavior of different salt solutions.

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